JP3040438B2 - Method for producing superabsorbent polymer - Google Patents
Method for producing superabsorbent polymerInfo
- Publication number
- JP3040438B2 JP3040438B2 JP2219454A JP21945490A JP3040438B2 JP 3040438 B2 JP3040438 B2 JP 3040438B2 JP 2219454 A JP2219454 A JP 2219454A JP 21945490 A JP21945490 A JP 21945490A JP 3040438 B2 JP3040438 B2 JP 3040438B2
- Authority
- JP
- Japan
- Prior art keywords
- water
- temperature
- oil
- phase
- polymerization
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired - Lifetime
Links
Classifications
-
- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08F—MACROMOLECULAR COMPOUNDS OBTAINED BY REACTIONS ONLY INVOLVING CARBON-TO-CARBON UNSATURATED BONDS
- C08F2/00—Processes of polymerisation
-
- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08F—MACROMOLECULAR COMPOUNDS OBTAINED BY REACTIONS ONLY INVOLVING CARBON-TO-CARBON UNSATURATED BONDS
- C08F2/00—Processes of polymerisation
- C08F2/32—Polymerisation in water-in-oil emulsions
Description
【発明の詳細な説明】 〔発明の背景〕 ＜産業上の利用分野＞ 本発明は、球状で大粒径であり、かつ流度分布が極め
て狭く、さらに残存有機溶媒の極めて少いさらさらとし
て流動性が極めて良い高吸水性ポリマーの製造法に関す
るものである。[Background of the Invention] <Industrial application field> The present invention relates to a fluid having a spherical shape, a large particle size, an extremely narrow flow distribution, and an extremely small amount of residual organic solvent. The present invention relates to a method for producing a superabsorbent polymer having extremely good properties.
本発明の方法によって得られる高吸水性ポリマーは、
多量の水を吸水して膨潤するが、水に不溶であり、球状
で粒子径が大きく、かつその粒度分布が極めて狭く、残
存有機溶媒が極めて少く、さらさらとして流動性が極め
て良いものであって、ハンドリング面及び安全性等極め
て高いものである。従って、本発明は、各種の吸収材料
および吸水として膨潤した状態で使用する各種の材料の
製造に好適に使用することができる。Superabsorbent polymer obtained by the method of the present invention,
It swells by absorbing a large amount of water, but is insoluble in water, is spherical and has a large particle size, and its particle size distribution is extremely narrow, the residual organic solvent is extremely small, and the fluidity is very good as a smooth. , Handling and safety are extremely high. Therefore, the present invention can be suitably used for the production of various absorbent materials and various materials used in a swollen state as water absorption.
＜従来の技術＞ 水性分散相中において水溶性エチレン性不飽和モノマ
ーを、該水溶液と実質的に相溶しない有機溶媒連続相中
で分散剤存在下に重合させて高吸水性ポリマーを製造す
る逆相懸濁重合法は、広く一般的に知られており、用い
る分散剤の種類、有機溶媒の種類、その他重合条件等に
特色ある重合法が報告されている。例えば分散剤として
HLB3〜６の非イオン界面活性剤を使用する方法（特公昭
54−30710号公報、特開昭61−157513号公報）、HLB6〜
９の非イオン界面活性剤（特開昭57−167302号公報）を
使用する方法、HLB8〜12の非イオン界面活性剤（特公昭
60−25045号公報等）を使用する方法、HLB2〜16のポリ
グリセリン脂肪酸エステルを使用する方法（特開昭62−
172006号公報）、ショ糖脂肪酸エステルを使用する方法
（特開昭61−87702号公報、特開昭61−43606号公報）、
セルロースエステル又はセルロースエーテルを使用する
方法（特開昭57−158210号公報）、メタクリル酸−メタ
クリル酸メチル−アクリル酸−２−エチルヘキシル共重
合体、無水マレイン酸変性ポリブタジエンとメタクリル
酸−２−ヒドロキシエチルとの反応物、ポリブタジエン
−メタクリル酸ブチル−メタクリル酸グラフト共重合
体、α，β−不飽和カルボン酸およびα，β−不飽和カ
ルボン酸のアルキルエステルまたはヒドロキシアルキル
エステルをグラフト重合したエチレン−プロピレン−ジ
エンモノマー共重合体等を使用する方法（特開昭57−94
011号公報）、その他α−オレフィンとα，β−不飽和
多価カルボン酸無水物との共重合体又はその誘導体を用
いる方法（特開昭62−95308号公報）等々が知られてい
る。<Related Art> A reverse process of producing a superabsorbent polymer by polymerizing a water-soluble ethylenically unsaturated monomer in an aqueous dispersion phase in an organic solvent continuous phase substantially incompatible with the aqueous solution in the presence of a dispersant. The phase suspension polymerization method is widely and generally known, and a polymerization method peculiar to the type of dispersant used, the type of organic solvent, and other polymerization conditions has been reported. For example, as a dispersant
Method using HLB 3-6 nonionic surfactant
54-30710, JP-A-61-157513), HLB6 ~
No. 9 non-ionic surfactant (JP-A-57-167302), HLB 8-12 non-ionic surfactant (Tokumisho)
No. 60-25045) and a method using a polyglycerol fatty acid ester of HLB2-16 (Japanese Patent Laid-Open No.
172006), a method using a sucrose fatty acid ester (JP-A-61-87702, JP-A-61-43606),
Method using cellulose ester or cellulose ether (JP-A-57-158210), methacrylic acid-methyl methacrylate-acrylic acid-2-ethylhexyl copolymer, maleic anhydride-modified polybutadiene and methacrylic acid-2-hydroxyethyl Reaction product, polybutadiene-butyl methacrylate-methacrylic acid graft copolymer, α-β-unsaturated carboxylic acid and ethylene-propylene graft-polymerized with an alkyl ester or hydroxyalkyl ester of α, β-unsaturated carboxylic acid. A method using a diene monomer copolymer or the like (JP-A-57-94)
No. 011) and a method using a copolymer of an α-olefin and an α, β-unsaturated polycarboxylic anhydride or a derivative thereof (JP-A-62-95308).
これら種々の方法によって得られる重合体は、その一
次粒子径が数μｍのものから数百μｍの比較的大きな球
状ポリマーとして得られるものの、一般的に数十μｍ以
下のいわゆる微粉ポリマーの生成はさけられず、粒度分
布としてはかなり幅の広いものとなっている。従って、
この為に粉体を取扱う場合の粉塵対策が必要となる。ま
た、一般的に微粉ポリマー量が増すことにより、被吸収
液を吸収する時にいわゆる“ままこ”現象を起し易く、
吸収が非常に困難となる。さらに、紙おむつや生理用ナ
プキンとして使用する場合など、粉砕パルプや不織布等
に吸水性ポリマーを混合保持させる場合に、微粉が脱落
しやすい等の問題を有している。Polymers obtained by these various methods can be obtained as relatively large spherical polymers having a primary particle diameter of several μm to several hundred μm, but generally avoid the formation of so-called finely divided polymers of several tens μm or less. However, the particle size distribution is rather wide. Therefore,
For this reason, it is necessary to take measures against dust when handling powder. In addition, generally, by increasing the amount of the finely divided polymer, a so-called “mamako” phenomenon easily occurs when absorbing the liquid to be absorbed,
Absorption becomes very difficult. In addition, when a water-absorbing polymer is mixed and held in pulverized pulp or nonwoven fabric, such as when used as a disposable diaper or a sanitary napkin, there is a problem that fine powder is likely to fall off.
また、前記逆相懸濁重合法によって得られるポリマー
には、重合時に使用する有機溶媒の同伴がさけられず、
一般的に数十〜数百重量ppm、多いものには数千重量pp
m、もの有機溶媒が残存するので、吸水性ポリマーを特
に紙おむつや生理用ナプキン等の様な衛生用材料として
使用する場合には、安全性の点で極めて問題となってい
る。Further, the polymer obtained by the reverse phase suspension polymerization method, the entrainment of the organic solvent used during the polymerization can not be avoided,
Generally dozens to hundreds of ppm by weight, most often thousands by weight pp
Since the organic solvent remains, the use of the water-absorbing polymer as a sanitary material such as a disposable diaper or a sanitary napkin is extremely problematic in terms of safety.
さらに、このように生成ポリマー中に有機溶媒が多量
に残存すると、一般的に粉体粒子のべとつきが大きくな
り、例えば紙おむつや生理用ナプキン製造プロセスにお
いて、ポリマーを粉体輸送する特に流動性が極めて悪い
ものとなってしまい、さらさらとした定量的な輸送が行
えないという極めて大きな問題点がある。Further, when a large amount of the organic solvent remains in the produced polymer, the stickiness of the powder particles generally increases, and for example, in the process of manufacturing a disposable diaper or a sanitary napkin, the flowability of the polymer powder is extremely low. There is a very big problem that it becomes bad and that it is not possible to carry out smooth quantitative transport.
＜要 旨＞ 本発明者等は、前記の問題点を解決する為に種々研究
を重ねた結果、モノマー水性液相を油相中に添加混合し
て、まず水中油滴型分散液に形成させ、しかる後に油中
水滴型に転相させた分散液中で水溶性不飽和モノマーを
重合させることにより、極めて一次粒子径が大きく、粒
度分布が狭く、かつ残存有機溶媒量の少い球状高吸水性
ポリマーが容易に、かつ低コストで得られることを見出
して本発明を完成するに至った。<Summary> The present inventors have conducted various studies in order to solve the above-mentioned problems, and as a result, the monomer aqueous liquid phase was added to and mixed with the oil phase to form an oil-in-water dispersion first. Then, by polymerizing the water-soluble unsaturated monomer in the dispersion liquid which has been phase-shifted to a water-in-oil type, a spherical high water absorption having a very large primary particle size, a narrow particle size distribution, and a small amount of residual organic solvent. The inventors have found that a conductive polymer can be obtained easily and at low cost, and have completed the present invention.
即ち、本発明による平均粒径80〜430μｍの高吸水性
ポリマーの製造法は、水溶性エチレン性不飽和モノマー
を、該水溶性エチレン性不飽和モノマー、水、水溶性重
合開始剤および必要に応じて水溶性架橋剤からなるモノ
マー水性溶液と分散剤を含む有機溶媒とからなる油中水
滴型の分散液中で逆相懸濁重合法により重合させて高吸
水性ポリマーを製造する方法において、有機溶媒中に該
モノマー水性溶液を添加し、水中油滴型の分散液となる
ような温度に保ち、しかる後に転相温度以上に昇温させ
て、前記の油中水滴型の分散液とすること、を特徴とす
るものである。That is, the method for producing a superabsorbent polymer having an average particle size of 80 to 430 μm according to the present invention comprises the steps of: converting a water-soluble ethylenically unsaturated monomer into the water-soluble ethylenically unsaturated monomer, water, a water-soluble polymerization initiator, and optionally In a method for producing a superabsorbent polymer by polymerizing by a reversed-phase suspension polymerization method in a water-in-oil type dispersion liquid comprising a monomer aqueous solution comprising a water-soluble crosslinking agent and an organic solvent containing a dispersant, The aqueous monomer solution is added to a solvent, and the temperature is maintained so as to be an oil-in-water type dispersion, and then the temperature is raised to a phase inversion temperature or higher to obtain the water-in-oil type dispersion. , Is characterized.
＜効 果＞ 本発明の製造法によって得られる高吸水性ポリマー
は、第一に、一次粒径が極めて大きく、かつその粒度分
布が狭いこと、第二に、ポリマー中の残存有機溶媒量が
極めて少く、さらさらとして流動性が極めて優れている
等の点において特に優れたものである。<Effects> The superabsorbent polymer obtained by the production method of the present invention has, firstly, an extremely large primary particle size and a narrow particle size distribution, and secondly, an extremely small amount of organic solvent remaining in the polymer. It is particularly excellent in that it has little fluidity and extremely excellent fluidity.
従って、その優れた取扱い性及び安全性を利用して、
生理用ナプキンや紙おしめ等をはじめとする種々衛生材
料、及び土壌改良剤や保水剤をはじめとする園芸用ない
し農業用等の各種の材料の製造に有利に使用することが
できる。Therefore, utilizing its excellent handling and safety,
It can be advantageously used in the production of various sanitary materials such as sanitary napkins and paper diapers, as well as various horticultural or agricultural materials such as soil conditioners and water retention agents.
本発明の重合法は、逆相懸濁重合法において、まず水
中油滴型に形成させ、しかる後に油中水滴型に転相させ
た分散液中で水溶性エチレン性不飽和モノマーを重合さ
せることを特徴とするものであるが、誤操作による前記
作用効果は分散液の転相現象からは全く想定しえない思
いがけないものというべきである。In the polymerization method of the present invention, in a reversed-phase suspension polymerization method, first, an oil-in-water type is formed, and then a water-soluble ethylenically unsaturated monomer is polymerized in a dispersion liquid which is phase-shifted to a water-in-oil type. However, the above-mentioned effects due to erroneous operation should be unexpected and cannot be expected at all from the phase inversion phenomenon of the dispersion liquid.
＜水溶性エチレン性不飽和モノマー＞ 本発明において使用される水溶性エチレン性不飽和モ
ノマーとしては、一般に吸水性を有するポリマーに転換
しうるものであればいずれのものでも使用できる。この
ような性能を与える水溶性のモノマーとしては、官能基
としてカルボン酸又は（及び）その塩、リン酸又は（及
び）その塩、スルホン酸又は（及び）その塩、あるいは
ヒドロキシル基、アミド基を有するエチレン性不飽和モ
ノマーが挙げられる。例えば（メタ）アクリル酸
（塩）、イタコン酸（塩）、ビニルスルホン酸（塩）、
ビニルホスホン酸（塩）、ポリエチレングリコール（メ
タ）アクリレート、（メタ）アクリルアミド等を挙げる
ことができる。ここで、「（メタ）アクリル」とはアク
リルおよびメタクリルの両者をいうものである。これら
は単独で用いることもできるし、２種以上併用すること
も可能である。これらのうちでは、特に、カルボン酸
（塩）官能基を有する水溶液性のエチレン性不飽和モノ
マーが好ましく、更には、アクリル酸又は（及び）メタ
クリル酸、及び（又は）これらのアルカリ金属塩または
アンモニウム塩がより好ましいものとして挙げられる。
本発明において最も好ましい水溶性エチレン性不飽和モ
ノマーは、アクリル酸を主成分とするものであって、そ
の全カルボキシル基の50〜95％がアルカリ金属塩又はア
ンモニウム塩に中和されてなるものである。<Water-soluble ethylenically unsaturated monomer> As the water-soluble ethylenically unsaturated monomer used in the present invention, any one can be used as long as it can be generally converted into a polymer having water absorbency. Examples of the water-soluble monomer giving such performance include carboxylic acid or (and) its salt, phosphoric acid or (and) its salt, sulfonic acid or (and) its salt, or hydroxyl group or amide group as a functional group. And an ethylenically unsaturated monomer having the same. For example, (meth) acrylic acid (salt), itaconic acid (salt), vinylsulfonic acid (salt),
Examples thereof include vinylphosphonic acid (salt), polyethylene glycol (meth) acrylate, and (meth) acrylamide. Here, “(meth) acryl” refers to both acryl and methacryl. These can be used alone or in combination of two or more. Among these, an aqueous ethylenically unsaturated monomer having a carboxylic acid (salt) functional group is particularly preferable, and further, acrylic acid or (and) methacrylic acid, and / or an alkali metal salt or ammonium thereof. Salts are more preferred.
The most preferred water-soluble ethylenically unsaturated monomer in the present invention contains acrylic acid as a main component, and is obtained by neutralizing 50 to 95% of all carboxyl groups with an alkali metal salt or an ammonium salt. is there.
これら水溶性エチレン性不飽和モノマーの水溶液中で
の濃度は、一般的には10重量％以上、好ましくは20重量
％〜飽和濃度、の条件が採用される。The concentration of these water-soluble ethylenically unsaturated monomers in an aqueous solution is generally at least 10% by weight, preferably from 20% by weight to a saturated concentration.
＜有機溶媒及び分散剤＞ 本発明で用いられる有機溶媒及び分散剤は、前記のよ
うなエチレン性不飽和モノマー水溶液が架橋剤（詳細後
記）の存在下または不存在下に、まず水中油滴型に形成
され、しかる後、転相して重合時に油中水滴型の分散液
が安定良く形成するものであればいかなるものも使用で
きる。このような有機溶媒及び分散剤は、（１）分散剤
としてα−オレフィンとα，β−不飽和多価カルボン酸
無水物との共重合体又はその誘導体を用い、ヒドロキシ
エチルセルロース存在下に炭化水素溶媒を用いる方法
（特開昭62−95308号、特開昭62−95307号各公報）、
（２）分散剤としてHLB3〜６のソルビタン脂肪酸エステ
ルを用い、石油系脂肪族炭化水素溶媒を用いる方法（特
公昭54−30710号公報）、（３）分散剤としてHLB3〜６
の非イオン界面活性剤を用い、脂肪族あるいは脂環族炭
化水素溶媒を用いる方法（特開昭61−157513号公報）、
（４）分散剤として油溶性のセルロースエステルまたは
セルロースエーテルを用い、炭化水素溶媒を用いる方法
（特開昭58−32607号公報）、（５）分散剤としてHLB6
〜９のノニオン系界面活性剤を用い、炭化水素溶媒を用
いる方法（特開昭57−167302号公報）、（６）分散剤と
してHLB8〜12のノニオン系界面活性剤を用い、脂肪族あ
るいは脂環族炭化水素溶媒を用いる方法（特開昭56−13
1608号公報）、（７）分散剤として塩基性窒素含有重合
体を用い、炭化水素溶媒を用いる方法（特開昭57−9851
3号公報）、（８）分散剤としてカルボキシル基含有重
合体を用い、炭化水素系溶媒を用いる方法（特開昭57−
94011号公報）、（９）分散剤としてショ糖脂肪酸エス
テルを用い、疎水性有機溶媒を用いる方法（特開昭61−
43606号公報、特開昭61−87702号公報）、（10）分散剤
として（Ａ）スチレン及び（又は）そのアルキル置換誘
導体50〜97モル％、（Ｂ）ジアルキルアミノアルキル−
アクリレートもしくは−メタクリレート及び（又は）ジ
アルキルアミノアルキル−アクリルアミドもしくは−メ
タクリルアミド３〜50モル％及び（Ｃ）（Ａ）及び
（Ｂ）と共重合し得る不飽和単量体０〜30モル％からな
る共重合体を用い、疎水性有機溶媒を用いる方法（特開
昭61−40309号公報）、（11）分散剤としてソルビタン
脂肪酸エステル及び（又は）ショ糖脂肪酸エステル、更
に（Ａ）スチレン及び（又は）そのアルキル置換誘導体
50〜97モル％、（Ｂ）ジアルキルアミノアルキル−アク
リレートもしくは−メタクリレート及び（又は）ジアル
キルアミノアルキル−アクリルアミドもしくは−メタク
リルアミド３〜50モル％及び（Ｃ）上記（Ａ）及び
（Ｂ）と共重合し得る不飽和単量体０〜30モル％からな
る共重合体を用い、疎水性有機溶媒を用いる方法（特開
昭61−53308号公報）、（12）分散剤としてHLB3〜９の
ソルビタン脂肪酸エステル及びポリオキシアルキレンモ
ノエーテル型の非イオン界面活性の混合物を用い、疎水
性溶媒を用いる方法（特開昭61−97301号公報）、（1
3）分散剤としてHLB2〜16のポリグリセリン脂肪酸エス
テルを使用し、石油系炭化水素溶媒を用いる方法（特開
昭62−172006号公報）、等において用いられているもの
を使用することができる。<Organic Solvent and Dispersant> The organic solvent and dispersant used in the present invention may be prepared by first preparing an aqueous solution of the ethylenically unsaturated monomer as described above in the presence or absence of a cross-linking agent (described in detail below) in the form of oil-in-water Any one can be used as long as it is phase-inverted and a stable water-in-oil type dispersion is formed during polymerization. Such an organic solvent and a dispersant are (1) a copolymer of an α-olefin and an α, β-unsaturated polycarboxylic anhydride or a derivative thereof as a dispersant, and a hydrocarbon in the presence of hydroxyethyl cellulose. A method using a solvent (JP-A-62-95308, JP-A-62-95307),
(2) A method using a sorbitan fatty acid ester of HLB 3 to 6 as a dispersant and a petroleum-based aliphatic hydrocarbon solvent (Japanese Patent Publication No. 54-30710), (3) HLB 3 to 6 as a dispersant
Using a nonionic surfactant and an aliphatic or alicyclic hydrocarbon solvent (JP-A-61-157513),
(4) A method in which an oil-soluble cellulose ester or cellulose ether is used as a dispersant and a hydrocarbon solvent is used (JP-A-58-32607). (5) HLB6 is used as a dispersant.
Using nonionic surfactants of Nos. 1 to 9 and a hydrocarbon solvent (JP-A-57-167302), (6) using nonionic surfactants of HLBs 8 to 12 as dispersants, and Method using a cyclic hydrocarbon solvent (JP-A-56-13)
No. 1608), (7) A method using a basic nitrogen-containing polymer as a dispersant and using a hydrocarbon solvent (Japanese Patent Laid-Open No. 57-9851).
No. 3) and (8) a method using a carboxyl group-containing polymer as a dispersant and a hydrocarbon solvent (Japanese Patent Application Laid-Open No.
94011), (9) A method using a sucrose fatty acid ester as a dispersant and a hydrophobic organic solvent (Japanese Unexamined Patent Publication No.
No. 43606, JP-A-61-87702), (10) 50-97 mol% of (A) styrene and / or an alkyl-substituted derivative thereof as a dispersant, and (B) dialkylaminoalkyl-
Acrylate or -methacrylate and / or dialkylaminoalkyl-acrylamide or -methacrylamide of 3 to 50 mol% and (C) 0 to 30 mol% of an unsaturated monomer copolymerizable with (A) and (B). A method using a copolymer and a hydrophobic organic solvent (JP-A-61-40309), (11) sorbitan fatty acid ester and / or sucrose fatty acid ester as a dispersant, and (A) styrene and / or ) Their alkyl substituted derivatives
50-97 mol%, (B) 3-50 mol% of dialkylaminoalkyl-acrylate or -methacrylate and / or dialkylaminoalkyl-acrylamide or -methacrylamide and (C) copolymerization with (A) and (B) above Using a copolymer comprising 0 to 30 mol% of an unsaturated monomer which can be used and a hydrophobic organic solvent (JP-A-61-53308), (12) sorbitan fatty acids of HLB 3 to 9 as dispersants A method in which a mixture of an ester and a polyoxyalkylene monoether type nonionic surfactant is used, and a hydrophobic solvent is used (JP-A-61-97301).
3) A polyglycerin fatty acid ester of HLB 2 to 16 is used as a dispersant, and a method using a petroleum hydrocarbon solvent (JP-A-62-172006) can be used.
本発明ではこれら有機溶媒及び分散剤の中でも、特に
有機溶媒として脂肪族あるいは脂環族炭化水素溶媒を用
い、分散剤としてHLB3〜９の非イオン界面活性剤を用い
る方法が好ましい例として挙げることができる。In the present invention, among these organic solvents and dispersants, in particular, a method using an aliphatic or alicyclic hydrocarbon solvent as an organic solvent and a method using a nonionic surfactant of HLB 3 to 9 as a dispersant may be mentioned as a preferred example. it can.
＜水溶性重合開始剤＞ 本発明で用いられる重合開始剤は、水溶性であり、か
つ前記の様な水溶性エチレン性不飽和モノマーの水溶液
中で溶解しうるものである。このようなものの具体例を
挙げれば、（イ）過酸化水素や過硫酸カリウム、過硫酸
ナトリウム、過硫酸アンモニウム等の過硫酸塩、（ロ）
ｔ−ブチルハイドロパーオキシドやクメンハイドロパー
オキシド等のハイドロパーオキシド類、（ハ）アゾイソ
ブチロニトリル、2,2′−アゾビス（２−アミジノプロ
パン）二塩酸塩等のアゾ系開始剤が用いられる。これら
の重合開始剤の中でも、特に、過硫酸塩、ハイドロパー
オキシド類等の様な酸化性を示す開始剤は、例えば亜硫
酸水素ナトリウム、Ｌ−アスコルビン酸、第一鉄塩等の
様な還元性物質あるいはアミン類との組合せによるレド
ックス開始剤としても用いることができる。<Water-soluble polymerization initiator> The polymerization initiator used in the present invention is water-soluble and can be dissolved in an aqueous solution of the above-mentioned water-soluble ethylenically unsaturated monomer. Specific examples of such substances include (a) hydrogen peroxide, persulfates such as potassium persulfate, sodium persulfate, and ammonium persulfate;
Hydroperoxides such as t-butyl hydroperoxide and cumene hydroperoxide, and azo initiators such as (c) azoisobutyronitrile and 2,2'-azobis (2-amidinopropane) dihydrochloride are used. Can be Among these polymerization initiators, particularly, initiators having an oxidizing property such as persulfates and hydroperoxides are examples of reducing initiators such as sodium bisulfite, L-ascorbic acid and ferrous salts. They can also be used as redox initiators in combination with substances or amines.
これら水溶性開始剤の使用量は、一般的には水溶性エ
チレン性不飽和モノマーに対して0.01〜10重量部％、好
ましくは0.1〜２重量％、である。The amount of these water-soluble initiators to be used is generally 0.01 to 10% by weight, preferably 0.1 to 2% by weight, based on the water-soluble ethylenically unsaturated monomer.
＜水溶性架橋剤＞ 本発明は、架橋剤存在下、又は不存在下のいずれの場
合でも行うことができ、重合反応により、あるいは重合
後の後処理によりポリマーが三次元化し、水その他溶媒
に対し不溶性となる条件が満されれば良い。<Water-soluble cross-linking agent> The present invention can be carried out either in the presence or absence of a cross-linking agent. The polymer becomes three-dimensional by a polymerization reaction or a post-treatment after polymerization, and is converted into water or another solvent. It suffices if the condition for insolubility is satisfied.
架橋を生起させる方法としては、例えば特公昭54−30
710号公報の様に架橋剤を用いず、アクリル酸塩の自己
架橋剤を用いて水不溶化させる方法、その他架橋剤を添
加して水不溶化する方法がある。架橋剤を添加して架橋
化させる方法としては、分子内に二重結合を２個以上有
し、前記水溶性エチレン性不飽和モノマーと共重合性を
示すもの、あるいは前記水溶性エチレン性不飽和モノマ
ー中の官能基、例えばカルボキシル基、と重合中あるい
は重合後の加熱乾燥時に反応しうるような官能基を２個
以上有するものである。これらは、ある程度水溶性で、
かつ前記エチレン性不飽和モノマー水溶液中に溶解する
ものであればいずれのものも使用できる。As a method of causing cross-linking, for example, Japanese Patent Publication No. 54-30
As disclosed in Japanese Patent No. 710, there are a method of insolubilizing water using a self-crosslinking agent of an acrylate salt without using a crosslinking agent, and a method of adding a crosslinking agent to water insolubilization. As a method of crosslinking by adding a crosslinking agent, a method having two or more double bonds in a molecule and showing copolymerizability with the water-soluble ethylenically unsaturated monomer, or the above-mentioned water-soluble ethylenically unsaturated monomer is used. It has two or more functional groups capable of reacting with a functional group in the monomer, for example, a carboxyl group, during polymerization or during heating and drying after polymerization. These are somewhat water soluble,
Any one can be used as long as it can be dissolved in the aqueous ethylenically unsaturated monomer solution.
前者の架橋剤としては、例えば、エチレングリコール
ジ（メタ）アクリレート、ジエチレングリコールジ（メ
タ）アクリレート、ポリエチレングリコールジ（メタ）
アクリレート、プロピレングリコールジ（メタ）アクリ
レート、ポリプロピレングリコールジ（メタ）アクリレ
ート、グリセリントリ（メタ）アクリレート、N,N′−
メチレンビス（メタ）アクリルアミド、ジアリルフタレ
ート、ジアリルマレート、ジアリルテレフタレート、ト
リアリルシアヌレート、トリアリルイソシアヌレート、
トリアリルホスフェート等が挙げられる。Examples of the former crosslinking agent include ethylene glycol di (meth) acrylate, diethylene glycol di (meth) acrylate, and polyethylene glycol di (meth) acrylate.
Acrylate, propylene glycol di (meth) acrylate, polypropylene glycol di (meth) acrylate, glycerin tri (meth) acrylate, N, N'-
Methylene bis (meth) acrylamide, diallyl phthalate, diallyl malate, diallyl terephthalate, triallyl cyanurate, triallyl isocyanurate,
Triallyl phosphate and the like.
また、後者の架橋剤の一例を挙げれば、エチレングリ
コールジグリシジルエーテル、ポリエチレングリコール
ジグリシジルエーテル、脂肪族多価アルコールのジ又は
ポリグリシジルエーテル等を挙げることができる。Examples of the latter crosslinking agent include ethylene glycol diglycidyl ether, polyethylene glycol diglycidyl ether, and di- or polyglycidyl ethers of aliphatic polyhydric alcohols.
更に、前者と後者の両機能を備えたものとして例えば
Ｎ−メチロールアクリルアミド、グリシジルメタアクリ
レート等のような化合物も本発明方法では使用できる。Further, compounds having both functions of the former and the latter, such as N-methylolacrylamide and glycidyl methacrylate, can be used in the method of the present invention.
この中で、本発明で特に好ましいものとして挙げれ
ば、分子中に二重結合を２個以上有し、前記水溶性エチ
レン性不飽和モノマーと共重合性を示すものが良い。Among them, particularly preferred in the present invention are those having two or more double bonds in the molecule and showing copolymerizability with the water-soluble ethylenically unsaturated monomer.
このような架橋剤はそれ自身単独で或いは２種以上の
混合物としても使用できる。Such a crosslinking agent can be used alone or as a mixture of two or more kinds.
これら架橋剤の使用量は、モノマーに対して0.001〜
５重量％、好ましくは0.01〜２重量％、である。The amount of these crosslinking agents used is 0.001 to
5% by weight, preferably 0.01 to 2% by weight.
＜転相及び重合操作＞ 本発明においては、前記に示した様な水溶性エチレン
性不飽和モノマーを、該水溶性エチレン性不飽和モノマ
ー、水、水溶性重合開始剤および必要により水溶性架橋
剤からなるモノマー水性溶液と分散剤含有有機溶媒とか
らなる分散液中で油中水滴型の逆相懸濁重合により重合
させる。この時、分散液は、有機溶媒中に該モノマー水
性溶媒を添加し、温度を比較的低温に保って先ず、水中
油滴型の分散液を形成させ、しかる後にこの分散液を水
中油滴型→油中水滴型の転相温度以上に昇温させること
によって油中水滴型分散液としたものであることが重要
である。<Phase Inversion and Polymerization Operation> In the present invention, the water-soluble ethylenically unsaturated monomer as described above is mixed with the water-soluble ethylenically unsaturated monomer, water, a water-soluble polymerization initiator and, if necessary, a water-soluble crosslinking agent. In a dispersion comprising a monomer aqueous solution consisting of: and a dispersant-containing organic solvent by water-in-oil type reverse phase suspension polymerization. At this time, the dispersion is prepared by adding the aqueous monomer solvent to an organic solvent and maintaining the temperature at a relatively low temperature to form an oil-in-water dispersion first. → It is important that the dispersion is formed into a water-in-oil type dispersion by raising the temperature to or above the water-in-oil type phase inversion temperature.
上記の様な転相操作は、特に転相温度は、用いる重合
条件、モノマー種、有機溶媒種、分散剤種及びそれらの
組成、モノマー相と油相との混合方法、分散系の昇温速
度等により著しく異なってくる。それらの一例は「工業
材料、第19巻第４号1971年度」に荒井により転相温度へ
の影響として紹介されており、用いる乳化剤の種類や
量、相容積比、炭化水素油種等々により著しく影響を受
けることが示されている。従って、本発明においてはそ
の操作条件を一義的に示すことは極めて困難であるが、
例えばモノマー種として部分中和アクリル酸ナトリウム
（中和度＝70モル％、水溶液中でのモノマー濃度＝30重
量％）、有機溶媒としてシクロヘキサン、分散剤として
ソルビタンモノステアレートを使用し、モノマー水性溶
液相対有機溶媒の容量比を0.7とし、両相を攪拌下混合
した場合の例を示せば、その転相温度は25℃であり、該
温度以下では水中油滴型をとり、それ以上では油中水滴
型となる。従ってこの様な場合、まず、部分中和アクリ
ル酸ナトリウム、水、水溶性重合開始剤、および必要に
より水溶性架橋剤からなるモノマー水性溶液相をシクロ
ヘキサン及びソルビタンモノステアレート中に添加、混
合して25℃以下とした水中油滴型の分散液を形成させ
る。次いで、攪拌下、加温により25℃以上として、油中
水滴型分散液に転相させて、所定の温度下、例えば60〜
70℃にて重合反応を行なわせる。尚、上記の様なモノマ
ー相と油相及びソルビタンモノステアレートなる分散剤
を混合して分散液とし、かつこの時の温度を25℃以下と
する方法としては、例えば下記の様な方法を挙げること
ができる。（１）予めソルビタンモノステアレートを油
相に溶解させた油相とモノマー相のそれぞれの温度を25
℃以下としたのち、油相の中にモノマー水溶液相を添加
混合してその混合物の温度を25℃以下とする方法、
（２）混合後の混合液の温度が25℃以下となる様な温度
にしたモノマー水溶液を、ソルビタンモノステアレート
を含む油相中に混合し、その混合物温度を25℃以下とす
る方法、（３）混合後の混合液の温度が25℃以下となる
様な温度のソルビタンモノステアレートを含む油相中
に、モノマー水溶液相を混合し、その混合物の温度を25
℃以下とする方法、（４）モノマー水溶液相をソルビタ
ンモノステアレートを含む油相中に注入後、混合液の温
度を25℃以下とする方法等々を挙げることができる。こ
のような低温では、分散液に重合開始剤が添加してあっ
ても、重合は事実上進行しないであろう。The phase inversion operation as described above, particularly the phase inversion temperature, depends on the polymerization conditions used, the type of monomer, the type of organic solvent, the type of dispersant and their composition, the method of mixing the monomer phase and the oil phase, the rate of temperature rise of the dispersion system It differs significantly depending on the situation. One example of these is introduced by Arai in "Industrial Materials, Vol. 19, No. 4, 1971" as the effect on the phase inversion temperature, and it depends on the type and amount of the emulsifier used, the phase volume ratio, the type of hydrocarbon oil, etc. It has been shown to be affected. Therefore, in the present invention, it is extremely difficult to uniquely indicate the operating conditions,
For example, using partially neutralized sodium acrylate as a monomer species (degree of neutralization = 70 mol%, monomer concentration in aqueous solution = 30% by weight), cyclohexane as an organic solvent, sorbitan monostearate as a dispersant, and a monomer aqueous solution If the volume ratio of the relative organic solvent is set to 0.7 and both phases are mixed with stirring, the phase inversion temperature is 25 ° C. It becomes a water drop type. Therefore, in such a case, first, a monomer aqueous solution phase composed of partially neutralized sodium acrylate, water, a water-soluble polymerization initiator, and, if necessary, a water-soluble crosslinking agent is added to cyclohexane and sorbitan monostearate and mixed. An oil-in-water dispersion at 25 ° C. or lower is formed. Next, under stirring, the temperature is raised to 25 ° C. or higher by heating, and the phase is changed to a water-in-oil dispersion, at a predetermined temperature, for example, 60 to 60 ° C.
The polymerization reaction is carried out at 70 ° C. In addition, as a method of mixing a dispersant such as a monomer phase, an oil phase and a sorbitan monostearate to form a dispersion, and setting the temperature at this time to 25 ° C. or lower, for example, the following method is used. be able to. (1) The temperature of each of the oil phase and the monomer phase in which sorbitan monostearate is previously dissolved in the oil phase is set to 25.
℃ or less, a method of adding and mixing the aqueous monomer solution phase into the oil phase to reduce the temperature of the mixture to 25 ℃ or less,
(2) a method of mixing an aqueous monomer solution having a temperature such that the temperature of the mixed liquid after mixing becomes 25 ° C. or less into an oil phase containing sorbitan monostearate, and adjusting the mixture temperature to 25 ° C. or less; 3) A monomer aqueous solution phase is mixed with an oil phase containing sorbitan monostearate at a temperature such that the temperature of the mixed solution after mixing is 25 ° C. or less, and the temperature of the mixture is lowered to 25 ° C.
C. or lower, and (4) a method of injecting the monomer aqueous solution phase into an oil phase containing sorbitan monostearate and then lowering the temperature of the mixed solution to 25 ° C. or lower. At such low temperatures, polymerization will not proceed effectively even if the polymerization initiator is added to the dispersion.
本発明における重合温度は、特に制限はなく、用いる
モノマー、重合開始剤、分散剤、あるいは有機溶媒等に
よって変化するが、水中油滴型分散液から油中水滴型へ
の転相温度以上であり、一般的には30〜150℃、通常40
〜100℃、が採用される。また、重合時間も特に制限は
なく、重合条件によって変化するが、一般的には５分〜
12時間、通常30分〜10時間、が採用される。The polymerization temperature in the present invention is not particularly limited, and varies depending on the monomer, polymerization initiator, dispersant, or organic solvent used, but is not lower than the phase transition temperature from the oil-in-water type dispersion to the water-in-oil type. , Generally 30-150 ° C, usually 40
~ 100 ° C is adopted. In addition, the polymerization time is not particularly limited, and varies depending on the polymerization conditions.
12 hours, usually 30 minutes to 10 hours, are employed.
重合後のポリマーは、ビーズ状の水を含んだ湿潤状態
として得られるがこれより脱水さらに所望の後処理、例
えばポリグリシジルエーテル等による表面架橋処理等を
経て、乾燥後、さらさらとした粉体状物質として得るこ
とが出来る。The polymer after polymerization is obtained in a wet state containing water in the form of beads, but is subjected to dehydration and further desired post-treatment, such as surface cross-linking treatment with polyglycidyl ether, etc. It can be obtained as a substance.
〔実 験 例〕 以下の実施例及び比較例は、更に本発明を詳細に説明
するものである。[Experimental Examples] The following Examples and Comparative Examples further illustrate the present invention in detail.
実施例１ 攪拌機、還流冷却器、温度計、窒素ガス導入管を付設
した容量１リットルの四つ口丸底フラスコに、シクロヘ
キサン303gを入れ、HLB4.7のソルビタンモノステアレー
ト2.25gを添加して溶解させ、氷冷下、内温を20℃とし
た。Example 1 In a 1-liter four-necked round-bottom flask equipped with a stirrer, a reflux condenser, a thermometer, and a nitrogen gas inlet tube, 303 g of cyclohexane was added, and 2.25 g of sorbitan monostearate having an HLB of 4.7 was added. After melting, the internal temperature was adjusted to 20 ° C. under ice cooling.
別に、容量500mlのフラスコ中でアクリル酸75gを外部
より氷冷しながら、これに水201gに溶解した31.2gの苛
性ソーダを加え、カルボキシル基の74.9％を中和した。
この場合の水に対するモノマー濃度は30重量％に相当す
る。次いで、これにN,N′−メチレンビスアクリルアミ
ド0.105g、過硫酸カリウム0.25gを加えて溶解させ氷冷
下20℃とした。Separately, 75 g of acrylic acid was externally ice-cooled in a flask having a capacity of 500 ml, and 31.2 g of caustic soda dissolved in 201 g of water was added thereto to neutralize 74.9% of carboxyl groups.
The monomer concentration in water in this case corresponds to 30% by weight. Next, 0.105 g of N, N'-methylenebisacrylamide and 0.25 g of potassium persulfate were added and dissolved, and the mixture was cooled to 20 ° C under ice cooling.
次いで、前記の四つ口フラスコの内容物に、攪拌下こ
の500mlのフラスコの内容物を添加し、氷冷下攪拌して
分散させ、窒素ガスをバブリングさせて溶存酸素を追い
出した。懸濁系混合物の内温は21℃となった。この時の
系は水中油滴型の分散液となった。次いで、窒素ガスを
バブリングさせながら油浴によりフラスコ内温を昇温さ
せたところ、25℃で系の分散状態が前記水中油滴型から
油中水滴に転相することが認められた。そこで引きつづ
き攪拌下、2.7℃/minの昇温速度にて昇温させ内温を60
〜65℃に保持し、４時間重合反応させた。尚、攪拌は25
0rpmで行った。Next, the contents of the 500-ml flask were added to the contents of the four-necked flask with stirring, dispersed with stirring under ice cooling, and nitrogen gas was bubbled to expel dissolved oxygen. The internal temperature of the suspension mixture was 21 ° C. The system at this time was an oil-in-water type dispersion. Next, when the temperature inside the flask was raised by an oil bath while bubbling nitrogen gas, it was confirmed that the dispersion state of the system was changed from the oil-in-water type to the water-in-oil type at 25 ° C. Then, with stirring, the temperature was raised at a rate of 2.7 ° C / min to raise the internal temperature to 60 ° C.
The temperature was kept at ℃ 65 ° C. to carry out a polymerization reaction for 4 hours. In addition, stirring is 25
Performed at 0 rpm.
４時間反応後、さらに攪拌下に油浴の温度を上げ、シ
クロヘキサンと水との共沸により、ポリマー中の水分が
約10重量％となる迄脱水処理を行った。After the reaction for 4 hours, the temperature of the oil bath was further increased with stirring, and dehydration treatment was performed by azeotropic distillation of cyclohexane and water until the water content in the polymer became about 10% by weight.
脱水処理後、攪拌を停止すると、さらさらとした湿潤
ポリマー粒子がフラスコの底に沈降したので、デカンテ
ーションでシクロヘキサン相と容易に分離できた。分離
した湿潤ポリマーを減圧乾燥器に移し、80〜90℃加熱し
て付着したシクロヘキサン及び水を除去したところ、さ
らさらとした塊のないポリマーとして得られた。When the stirring was stopped after the dehydration treatment, the free flowing wet polymer particles settled at the bottom of the flask, and thus could be easily separated from the cyclohexane phase by decantation. The separated wet polymer was transferred to a reduced-pressure drier and heated at 80 to 90 ° C. to remove attached cyclohexane and water.
実施例２（有機溶媒種の影響） 実施例１においてシクロヘキサンのかわりにｎ−ヘキ
サンを使用し重合温度を55〜60℃とした以外は同処方、
同操作にて重合を行った。この場合の転相温度は28℃で
あることが認められ、重合、脱水及び乾燥を経てさらさ
らとした塊のないポリマーが得られた。Example 2 (Effect of Organic Solvent Type) The same formulation as in Example 1 except that n-hexane was used instead of cyclohexane and the polymerization temperature was 55-60 ° C.
Polymerization was performed by the same operation. In this case, the phase inversion temperature was found to be 28 ° C., and a polymer free of lumps was obtained after polymerization, dehydration and drying.
実施例３（有機溶媒種の影響） 実施例１においてシクロヘキサンのかわりにｎ−ヘプ
タンを使用し、重合温度を65〜75℃とした以外は同処
方、同操作にて重合を行った。この場合の転相温度は32
℃であることが認められ、重合、脱水及び乾燥を経てさ
らさらとした塊のないポリマーが得られた。Example 3 (Effect of Organic Solvent Type) Polymerization was carried out in the same manner as in Example 1 except that n-heptane was used instead of cyclohexane and the polymerization temperature was 65 to 75 ° C. The phase inversion temperature in this case is 32
° C, and a polymer free of lumps was obtained after polymerization, dehydration and drying.
実施例４（有機溶媒種、モノマー濃度の影響） 攪拌機、還流冷却器、滴下ロート、窒素ガス導入管を
付した500mlの四つ口丸底フラスコに、ｎ−ヘキサン228
mlを入れ、HLB4.7のソルビタンモノステアレート1.8gを
添加して溶解させたのち、氷冷下内温を15℃とした。Example 4 (Effect of Organic Solvent Type and Monomer Concentration) In a 500 ml four-necked round bottom flask equipped with a stirrer, a reflux condenser, a dropping funnel and a nitrogen gas introducing tube, n-hexane 228 was added.
Then, 1.8 g of sorbitan monostearate of HLB4.7 was added and dissolved, and the internal temperature was adjusted to 15 ° C. under ice cooling.
別に、三角フラスコ中でアクリル酸30gを外部より氷
冷しながら、これに水39gに溶解した13.1gの純度95％苛
性ソーダの水溶液を加えて、カルボキシル基の75％を中
和した。水相中のモノマー濃度は45重量％となった。次
いで、過硫酸カリウム0.1gを加えて溶解させ、氷冷下15
℃とした。次いで、この三角フラスコの内容物を、攪拌
下上記の四つ口フラスコに加えて分散させ、窒素ガスを
バブリングさせ溶存酸素を追い出した。懸濁系の温度は
16℃となった。この時の系は水中油滴型の分散状態とな
った。Separately, while cooling 30 g of acrylic acid from outside in an Erlenmeyer flask, an aqueous solution of 13.1 g of 95% pure caustic soda dissolved in 39 g of water was added thereto to neutralize 75% of the carboxyl groups. The monomer concentration in the aqueous phase was 45% by weight. Next, 0.1 g of potassium persulfate was added to dissolve, and the mixture was cooled under ice cooling for 15 minutes.
° C. Next, the contents of this Erlenmeyer flask were added to the above-mentioned four-necked flask with stirring to disperse, and nitrogen gas was bubbled to dissolve dissolved oxygen. The temperature of the suspension is
The temperature reached 16 ° C. At this time, the system was in an oil-in-water type dispersion state.
次いで窒素ガスを少量ずつ導入しながら油浴によりフ
ラスコ内容物を昇温させたところ21℃にて系の分散状態
が前記水中油滴型から油中水滴型に転相することが認め
られた。そこで引き続きフラスコ内容物を攪拌下、2.7
℃/minの昇温速度にて昇温させ、内温を60〜65℃に保持
し、６時間反応を行わせた。Then, the contents of the flask were heated by an oil bath while introducing nitrogen gas little by little. As a result, at 21 ° C., it was recognized that the dispersion state of the system changed from the oil-in-water type to the water-in-oil type. Therefore, the contents of the flask were continuously stirred under 2.7
The temperature was increased at a rate of ° C / min, the internal temperature was maintained at 60 to 65 ° C, and the reaction was performed for 6 hours.
反応後、さらに攪拌下の油浴の温度を調節し、ｎ−ヘ
キサンと水との共沸により、ポリマー中の水分が約10重
量％となる迄脱水処理を行った。After the reaction, the temperature of the oil bath under stirring was further adjusted, and dehydration treatment was performed by azeotropic distillation of n-hexane and water until the water content in the polymer became about 10% by weight.
脱水処理後攪拌を停止すると、さらさらとした湿潤ポ
リマー粒子がフラスコの底に沈降したのでデカンテーシ
ョンでｎ−ヘキサンを容易に分離できた。分離した湿潤
ポリマーを減圧乾燥器に移し、80〜90℃に加熱して付着
したｎ−ヘキサン及び水を除去したところ、さらさらし
た塊のないポリマーとして得られた。When the stirring was stopped after the dehydration treatment, the smooth polymer particles settled at the bottom of the flask, so that n-hexane could be easily separated by decantation. The separated wet polymer was transferred to a reduced-pressure drier and heated to 80 to 90 ° C. to remove adhering n-hexane and water. As a result, a free-flowing lump-free polymer was obtained.
実施例５（混合方法の影響） 実施例１において、１リットルの四つ口丸底フラスコ
の内容物に静置、即ち無攪拌下、500mlのフラスコの内
容物を添加した。次いで氷冷下内容物を攪拌して分散さ
せ、窒素ガスをバブリングさせて溶存酸素を追い出し
た。懸濁系混合物の内温は21℃となった。この時の系は
水中油滴型の分散状態となった。次いで窒素ガスをバブ
リングさせながら油浴によりフラスコ内温を0.5℃/min
にて、攪拌下昇温させたところ、40℃にて系の分散状態
が前記水中油滴型から油中水滴型に転相することが認め
られた。そこで引き続き攪拌下同速度にて昇温させ、内
温を60〜65℃に保持し、４時間反応させた。尚、攪拌は
250rpmで行った。Example 5 (Effect of Mixing Method) In Example 1, the contents of a 500-ml flask were allowed to stand still, that is, without stirring, in the contents of a 1-liter four-necked round bottom flask. Then, the contents were stirred and dispersed under ice cooling, and dissolved oxygen was expelled by bubbling nitrogen gas. The internal temperature of the suspension mixture was 21 ° C. At this time, the system was in an oil-in-water type dispersion state. Then, while bubbling nitrogen gas, the temperature inside the flask was adjusted to 0.5 ° C / min by an oil bath.
When the temperature was increased with stirring, it was confirmed that the dispersion state of the system at 40 ° C. changed from the oil-in-water type to the water-in-oil type. Then, the temperature was increased at the same rate with continuous stirring, the internal temperature was maintained at 60 to 65 ° C, and the reaction was carried out for 4 hours. In addition, stirring
Performed at 250 rpm.
４時間反応後、さらに攪拌下に油浴の温度を上げ、シ
クロヘキサンと水との共沸により、ポリマー中の水分が
約10重量％となる迄脱水処理を行った。After the reaction for 4 hours, the temperature of the oil bath was further increased with stirring, and dehydration treatment was performed by azeotropic distillation of cyclohexane and water until the water content in the polymer became about 10% by weight.
脱水処理後、攪拌を停止すると、さらさらとした湿潤
ポリマー粒子がフラスコの底に沈降したので、デカンテ
ーションでシクロヘキサン相と容易に分離できた。分離
した湿潤ポリマーを減圧乾燥器に移し、80〜90℃加熱し
て付着したシクロヘキサン及び水を除去したところ、さ
らさらとした塊のないポリマーとして得られた。When the stirring was stopped after the dehydration treatment, the free flowing wet polymer particles settled at the bottom of the flask, and thus could be easily separated from the cyclohexane phase by decantation. The separated wet polymer was transferred to a reduced-pressure drier and heated at 80 to 90 ° C. to remove attached cyclohexane and water.
実施例６（昇温速度の影響） 実施例５においてフラスコ内温の昇温速度を１℃/min
とした以外は同操作条件にて行ったところ、50℃にて水
中油滴型の分散状態から油中水滴型分散状態に転相する
ことが認められた。そして同処方、同操作にて重合反
応、脱水及び乾燥処理を経てさらさらとした塊のないポ
リマーを得た。Example 6 (Effect of Heating Rate) In Example 5, the heating rate of the internal temperature of the flask was changed to 1 ° C./min.
Under the same operating conditions as above, it was confirmed that at 50 ° C., the phase changed from the oil-in-water dispersion state to the water-in-oil dispersion state. The polymer was subjected to a polymerization reaction, a dehydration and a drying treatment by the same formulation and the same operation to obtain a free-flowing lump-free polymer.
実施例７（分散剤種の影響） 実施例１においてソルビタンモノステアレートのかわ
りにHLB＝5.0のジグリセリルモノステアレートを使用し
た以外は同処方、同操作にて重合を行った。この場合の
転相温度は20℃であることが認められ、重合、脱水、及
び乾燥を経てさらさらとした塊のないポリマーが得られ
た。Example 7 (Effect of Dispersant Type) Polymerization was carried out in the same manner as in Example 1 except that diglyceryl monostearate having an HLB of 5.0 was used instead of sorbitan monostearate. In this case, the phase inversion temperature was found to be 20 ° C., and a polymer free of lumps was obtained after polymerization, dehydration, and drying.
実施例８（溶媒種、分散剤種呼びモノマー濃度の影響） 攪拌機、還流冷却器、温度計、窒素ガス導入管を付し
た500mlの四つ口丸底フラスコにｎ−ヘプタン280mlをと
り、HLB3.5のデカグリセリルペンタステアレート0.75g
を添加溶解させ、内温を20℃とした。Example 8 (Effect of Solvent Type, Dispersant Type and Monomer Concentration) In a 500 ml four-necked round bottom flask equipped with a stirrer, a reflux condenser, a thermometer, and a nitrogen gas inlet tube, 280 ml of n-heptane was placed. 0.75 g of decaglyceryl pentastearate of 5
Was added and dissolved, and the internal temperature was adjusted to 20 ° C.
別に200mlの三角フラスコ中に30gのアクリル酸、水7.
5gを採り、外部より冷却しつつ、25.4重量％の苛性ソー
ダ水溶液49.3gを添加し75モル％の中和を行った。この
場合、水に対するモノマー濃度は43重量％に相当する。
次いで過硫酸カリウム0.05gを加えて溶解し、内温を20
℃とした。Separately 30 g of acrylic acid and water in a 200 ml Erlenmeyer flask 7.
5 g was taken, and while cooling from the outside, 49.3 g of a 25.4% by weight aqueous solution of caustic soda was added to neutralize 75 mol%. In this case, the monomer concentration with respect to water corresponds to 43% by weight.
Next, 0.05 g of potassium persulfate was added and dissolved, and the internal temperature was lowered to 20 g.
° C.
このアクリル酸部分中和塩水溶液を四つ口フラスコに
攪拌下加えて分散させ、窒素ガスをバブリングして溶存
酸素を追い出した。懸濁系の温度は20℃であった。この
時の系は水中油滴型の分散状態となった。そこで窒素ガ
スをバブリングさせながら油浴によりフラスコ内温を昇
温させたところ、25℃にて系の分散状態が前記水中油滴
型から油中水滴型に転相することが認められた。This aqueous solution of partially neutralized acrylic acid salt was added to a four-necked flask with stirring to disperse the solution, and dissolved oxygen was expelled by bubbling nitrogen gas. The temperature of the suspension was 20 ° C. At this time, the system was in an oil-in-water type dispersion state. Then, when the temperature inside the flask was raised by an oil bath while bubbling nitrogen gas, it was confirmed that the dispersion state of the system changed from the oil-in-water type to the water-in-oil type at 25 ° C.
次いで、さらに窒素ガスを少量ずつ導入しながら、油
浴によりフラスコ内容物を2.7℃/minにて昇温させ、油
浴温度を55〜65℃に保持して２時間重合を行った。反応
後、攪拌下油浴の温度を調節し、ｎ−ヘプタンと水との
共沸により、ポリマー中の水分が約10重量％となる迄脱
水処理した。Then, while introducing nitrogen gas little by little, the contents of the flask were heated at 2.7 ° C / min by an oil bath, and polymerization was carried out for 2 hours while maintaining the oil bath temperature at 55 to 65 ° C. After the reaction, the temperature of the oil bath was adjusted with stirring, and the polymer was dehydrated by azeotropic distillation of n-heptane and water until the water content in the polymer became about 10% by weight.
脱水処理後、攪拌を停止するとさらさらとした湿潤ポ
リマー粒子がフラスコの底に沈降したのでデカンテーシ
ョンでｎ−ヘプタンを容易に分離できた。When the stirring was stopped after the dehydration treatment, the free flowing wet polymer particles settled at the bottom of the flask, so that n-heptane could be easily separated by decantation.
分離した湿潤ポリマーを減圧乾燥器に移し、80〜90℃
に加熱し、付着したｎ−ヘプタン及び水を除去したとこ
ろ、さらさらとした塊のないポリマーとして得られた。Transfer the separated wet polymer to a vacuum dryer, 80-90 ° C
After heating to remove the attached n-heptane and water, the polymer was obtained as a free-flowing, lump-free polymer.
比較例１ 実施例１において、シクロヘキサン、ソルビタンモノ
ステアレートから成る油相の温度を30℃とし、水、アク
リル酸、アクリル酸ソーダ、N,N′−メチレンビスアク
リルアミド、過硫酸カリウムから成る水相の温度を30℃
とし、両相を混合して、懸濁状混合物とし、その内温を
30℃とした以外は、同操作、同処方にて重合、脱水、及
び乾燥を行った。この懸濁状態においては油中水滴型の
分散液であり、重合反応も同状態にて行った。Comparative Example 1 In Example 1, the temperature of the oil phase composed of cyclohexane and sorbitan monostearate was 30 ° C., and the aqueous phase composed of water, acrylic acid, sodium acrylate, N, N′-methylenebisacrylamide, and potassium persulfate 30 ℃
And the two phases are mixed to form a suspended mixture.
Polymerization, dehydration, and drying were performed by the same operation and the same formulation except that the temperature was changed to 30 ° C. This suspension was a water-in-oil type dispersion, and the polymerization reaction was carried out in the same state.
比較例２ 実施例２において、ｎ−ヘキサン、ソルビタンモノス
テアレートから成る油相の温度を34℃とし、水、アクリ
ル酸、アクリル酸ソーダ、N,N′−メチレンビスアクリ
ルアミド、過硫酸カリウムから成る水相の温度を34℃と
し、両相を混合して、懸濁状混合物とし、その内温を34
℃とした以外は同操作、同処方にて重合、脱水、及び乾
燥を行った。この懸濁状態においては油中水滴型の分散
液であり、重合反応も同状態にて行った。Comparative Example 2 In Example 2, the temperature of the oil phase consisting of n-hexane and sorbitan monostearate was set to 34 ° C. and consisted of water, acrylic acid, sodium acrylate, N, N′-methylenebisacrylamide, and potassium persulfate. The temperature of the aqueous phase is brought to 34 ° C., and the two phases are mixed to form a suspended mixture, the internal temperature of which is 34 ° C.
Polymerization, dehydration, and drying were performed by the same operation and the same formulation except that the temperature was changed to ° C. This suspension was a water-in-oil type dispersion, and the polymerization reaction was carried out in the same state.
比較例３ 実施例３において、ｎ−ヘプタン、ソルビタンモノス
テアレートから成る油相の温度を37℃とし、水、アクリ
ル酸、アクリル酸ソーダ、N,N′−メチレンビスアクリ
ルアミド、過硫酸カリウムから成る水相の温度を37℃と
し、両相を混合して、懸濁状混合物とし、その内温を37
℃とした以外は同操作、同処方にて重合、脱水、及び乾
燥を行った。この懸濁状態においては油中水滴型の分散
液であり、重合反応も同状態にて行った。Comparative Example 3 In Example 3, the temperature of the oil phase consisting of n-heptane and sorbitan monostearate was 37 ° C., and it consisted of water, acrylic acid, sodium acrylate, N, N′-methylenebisacrylamide, and potassium persulfate. The temperature of the aqueous phase was adjusted to 37 ° C., and the two phases were mixed to form a suspended mixture.
Polymerization, dehydration, and drying were performed by the same operation and the same formulation except that the temperature was changed to ° C. This suspension was a water-in-oil type dispersion, and the polymerization reaction was carried out in the same state.
比較例４ 実施例７において、シクロヘキサン、ジグリセリルモ
ノステアレートから成る油相の温度を30℃とし、水、ア
クリル酸、アクリル酸ソーダ、N,N′−メチレンビスア
クリルアミド、過硫酸カリウムから成る水相の温度を30
℃とし、両相を混合して、懸濁状混合物とし、その内温
を30℃とした以外は、同操作、同処方にて重合、脱水、
及び乾燥を行った。この懸濁状態においては油中水滴型
の分散液であり、重合反応も同状態にて行った。Comparative Example 4 In Example 7, the temperature of the oil phase composed of cyclohexane and diglyceryl monostearate was set to 30 ° C., and water composed of water, acrylic acid, sodium acrylate, N, N′-methylenebisacrylamide, and potassium persulfate was used. Phase temperature 30
° C., both phases were mixed to form a suspended mixture, and the same operation and polymerization, dehydration,
And drying. This suspension was a water-in-oil type dispersion, and the polymerization reaction was carried out in the same state.
比較例５ 実施例８においてｎ−ヘプタン、デカグリセリルペン
タステアレートから成る油相の温度を30℃とし、水、ア
クリル酸、アクリル酸ソーダ、過硫酸カリウムから成る
水相の温度を30℃、両相を混合して懸濁状混合物とし、
その内温を30℃とした以外は、同操作、同処方にて重
合、脱水、及び乾燥を行った。この懸濁状態においては
油中水滴型分散液であり、重合反応も同状態にて行っ
た。Comparative Example 5 In Example 8, the temperature of the oil phase composed of n-heptane and decaglyceryl pentastearate was 30 ° C., and the temperature of the aqueous phase composed of water, acrylic acid, sodium acrylate and potassium persulfate was 30 ° C. Mixing the phases into a suspension mixture,
Polymerization, dehydration, and drying were performed by the same operation and the same formulation except that the internal temperature was 30 ° C. This suspension was a water-in-oil dispersion, and the polymerization reaction was carried out in the same state.
以上の各実施例及び比較例で得られたポリマーについ
て下記に示す方法により食塩水吸収倍率、残存有機溶媒
量、粒径分布及び平均粒子径についての各試験を行っ
た。その結果を表１に示す。Each of the polymers obtained in each of the above Examples and Comparative Examples was subjected to each test for the absorption capacity of saline solution, the amount of the remaining organic solvent, the particle size distribution, and the average particle size by the methods described below. Table 1 shows the results.
（１）食塩水吸水倍率 300mlのビーカーにポリマー約1.0g及び濃度0.9重量％
の食塩水約200gをそれぞれ秤量して入れ、混合してから
約60分間放置して、食塩水によってポリマーを十分に膨
潤させた。次いで100メッシュフルイで水切りをしたの
ち、膨潤ゲルを測定して下記式により食塩水吸水倍率を
算出した。(1) About 1.0 g of polymer and 0.9% by weight in a 300 ml beaker
Approximately 200 g of each saline solution was weighed, mixed, and allowed to stand for about 60 minutes to sufficiently swell the polymer with the saline solution. Next, after draining with a 100 mesh sieve, the swollen gel was measured and the water absorption capacity of the saline solution was calculated by the following formula.
（２）残存有機溶媒量 ポリマー数10mgを精秤し、加熱炉型熱分解装置に入
れ、270℃で、ヘリウムを流しながら10分間、熱抽出を
行なった。抽出された有機溶媒をガスクロマトグラフの
分離カラムの先端にコールドトラップし、炭化水素専用
キャピラリーカラム（水素炎イオン化検出器付）にて定
量した。更にこの操作を有機溶媒が抽出されなくなるま
で繰り返して、積算し、トータル量をもって、残存の有
機溶媒量とした。 (2) Amount of residual organic solvent Ten mg of the polymer was precisely weighed, placed in a heating furnace type pyrolysis apparatus, and subjected to heat extraction at 270 ° C. for 10 minutes while flowing helium. The extracted organic solvent was cold-trapped at the tip of a separation column of a gas chromatograph, and quantified by a hydrocarbon-dedicated capillary column (with a flame ionization detector). This operation was repeated until the organic solvent was no longer extracted, integrated, and the total amount was defined as the amount of the remaining organic solvent.
（３）粒径分布 ASTM式標準フルイを上から20メッシュ、40メッシュ、
60メッシュ、80メッシュ、100メッシュ、150メッシュ、
200メッシュ、270メッシュ、325メッシュ、受け皿の順
に組み合わせ、最上のフルイにポリマーを約30g入れ、
ロータップ型自動フルイ振とう器にて１分間振とうさせ
た。後、各フルイに残ったポリマーの重量を秤量し、全
体量を100％とする割合を算出し、質量基準の粒径分布
とした。(3) Particle size distribution 20 mesh, 40 mesh,
60 mesh, 80 mesh, 100 mesh, 150 mesh,
200 mesh, 270 mesh, 325 mesh, combine in the order of the saucer, put about 30 g of polymer in the top screen,
The mixture was shaken for 1 minute using a low-tap automatic sieve shaker. Thereafter, the weight of the polymer remaining in each sieve was weighed, and the ratio of the total amount to 100% was calculated to obtain a mass-based particle size distribution.
（４）平均粒径 対数目盛の横軸に粒子径、確率目盛の縦軸に積算フル
イ下％（質量基準）をプロットし、積算フルイ下％が50
％の際の粒子径を平均粒径とした。(4) Average particle size The particle diameter is plotted on the horizontal axis of the logarithmic scale, and the integrated screen lower% (mass basis) is plotted on the vertical axis of the probability scale.
% Was defined as the average particle size.
フロントページの続き (56)参考文献 特開 平２−284902（ＪＰ，Ａ) (58)調査した分野(Int.Cl.7，ＤＢ名) C08F 2/32 Continuation of the front page (56) References JP-A-2-284902 (JP, A) (58) Fields investigated (Int. Cl. 7 , DB name) C08F 2/32
Claims (1)
溶性エチレン性不飽和モノマー、水、水溶性重合開始剤
および必要に応じて水溶性架橋剤からなるモノマー水性
溶液と分散剤を含む有機溶媒とからなる油中水滴型の分
散液中で逆相懸濁重合法により重合させて高吸水性ポリ
マーを製造する方法において、有機溶媒中に該モノマー
水性溶液を添加し、水中油滴型の分散液となるような温
度に保ち、しかる後に転相温度以上に昇温させて、前記
の油中水滴型の分散液とすることを特徴とする、平均粒
径80〜430μｍの高吸水性ポリマーの製造法。An organic solvent containing a water-soluble ethylenically unsaturated monomer, an aqueous solution of a monomer comprising the water-soluble ethylenically unsaturated monomer, water, a water-soluble polymerization initiator and, if necessary, a water-soluble crosslinking agent, and a dispersant. In a method of producing a superabsorbent polymer by polymerizing by a reversed-phase suspension polymerization method in a water-in-oil type dispersion liquid comprising a solvent, the monomer aqueous solution is added to an organic solvent, an oil-in-water type The dispersion is maintained at a temperature such that it becomes a dispersion, and thereafter, the temperature is raised to the phase inversion temperature or higher to obtain the above-mentioned water-in-oil type dispersion, and the highly water-absorbing polymer having an average particle size of 80 to 430 μm. Manufacturing method.
Priority Applications (6)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP2219454A JP3040438B2 (en) | 1990-08-21 | 1990-08-21 | Method for producing superabsorbent polymer |
| TW080106307A TW203061B (en) | 1990-08-21 | 1991-08-09 | |
| EP91307526A EP0472362B1 (en) | 1990-08-21 | 1991-08-14 | Process for the production of highly water absorptive polymers |
| DE69116264T DE69116264T2 (en) | 1990-08-21 | 1991-08-14 | Process for the production of highly water-absorbent polymers |
| US07/746,991 US5202400A (en) | 1990-08-21 | 1991-08-19 | Process for the production of highly water absorptive polymers |
| KR1019910014372A KR100196562B1 (en) | 1990-08-21 | 1991-08-21 | Process for the production of highly water absorptive polymers |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP2219454A JP3040438B2 (en) | 1990-08-21 | 1990-08-21 | Method for producing superabsorbent polymer |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPH04100803A JPH04100803A (en) | 1992-04-02 |
| JP3040438B2 true JP3040438B2 (en) | 2000-05-15 |
Family
ID=16735678
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP2219454A Expired - Lifetime JP3040438B2 (en) | 1990-08-21 | 1990-08-21 | Method for producing superabsorbent polymer |
Country Status (6)
| Country | Link |
|---|---|
| US (1) | US5202400A (en) |
| EP (1) | EP0472362B1 (en) |
| JP (1) | JP3040438B2 (en) |
| KR (1) | KR100196562B1 (en) |
| DE (1) | DE69116264T2 (en) |
| TW (1) | TW203061B (en) |
Families Citing this family (22)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| FR2730176B1 (en) * | 1995-02-02 | 1997-04-11 | Fcb | HIGH INTENSITY MAGNETIC SEPARATOR OF THE ROTOR AND ENDLESS BELT TYPE |
| US5565019A (en) * | 1995-04-04 | 1996-10-15 | Ashland Inc. | Process for increasing the system thermal capability of a splash filled cooling tower |
| US5624676A (en) * | 1995-08-03 | 1997-04-29 | The Procter & Gamble Company | Lotioned tissue paper containing an emollient and a polyol polyester immobilizing agent |
| US5705164A (en) * | 1995-08-03 | 1998-01-06 | The Procter & Gamble Company | Lotioned tissue paper containing a liquid polyol polyester emollient and an immobilizing agent |
| US5607760A (en) * | 1995-08-03 | 1997-03-04 | The Procter & Gamble Company | Disposable absorbent article having a lotioned topsheet containing an emollient and a polyol polyester immobilizing agent |
| US5609587A (en) * | 1995-08-03 | 1997-03-11 | The Procter & Gamble Company | Diaper having a lotioned topsheet comprising a liquid polyol polyester emollient and an immobilizing agent |
| DE19601763A1 (en) * | 1996-01-19 | 1997-07-24 | Hoechst Ag | Use of surfactants in the drying of hydrophilic, highly swellable hydrogels |
| AU717286B2 (en) * | 1996-11-06 | 2000-03-23 | Sanyo Chemical Industries Ltd. | Water absorbing agent and absorbent material |
| KR100545673B1 (en) * | 1998-06-22 | 2006-05-23 | 송원산업주식회사 | Manufacturing method of porous absorbent resin |
| JP2005270414A (en) * | 2004-03-25 | 2005-10-06 | Ebisu Kasei Co Ltd | Cushioning body with faint perfume |
| KR100629398B1 (en) | 2005-06-20 | 2006-09-27 | 이양화학주식회사 | Preparation method of water-in-oil type polymer flocculant for sea water |
| EP2014683B1 (en) | 2006-04-27 | 2012-10-10 | Sumitomo Seika Chemicals Co., Ltd. | Process for production of water-absorbable resin |
| CN101589066B (en) | 2007-01-24 | 2013-07-03 | 株式会社日本触媒 | Particulate water-absorbent polymer and process for production thereof |
| WO2009025235A1 (en) * | 2007-08-23 | 2009-02-26 | Sumitomo Seika Chemicals Co., Ltd. | Water-absorbing resin suitable for use in sanitary products |
| EP2265647A4 (en) * | 2008-03-31 | 2014-11-26 | RHODIA OPéRATIONS | Self-situating stimuli-responsive polymer compositions in soil additives and methods for use |
| UA109772C2 (en) | 2009-07-02 | 2015-10-12 | AGENT FOR IMPROVING SOIL HYDROPHILITY AND APPLICATION METHODS | |
| AU2010323629A1 (en) * | 2009-11-27 | 2012-07-19 | Sumitomo Seika Chemicals Co., Ltd. | Process for production of water-absorbing resin particles, water-absorbing resin particles, water-stopping material, and absorbent article |
| US8728659B2 (en) * | 2010-05-28 | 2014-05-20 | Spectrum Brands, Inc. | Alkaline cell with additive for improved discharge performance |
| WO2012014749A1 (en) | 2010-07-28 | 2012-02-02 | 住友精化株式会社 | Process for production of water-absorbable resin |
| WO2012022046A1 (en) | 2010-08-20 | 2012-02-23 | Rhodia (China) Co., Ltd. | Soil additives for prevention of evaporation and methods for use |
| HUE056081T2 (en) | 2011-02-28 | 2022-01-28 | Rhodia Operations | Seed coatings, coating compositions and methods for use |
| US10745578B2 (en) * | 2011-02-28 | 2020-08-18 | Rhodia Operations | Seed coatings, coating compositions and methods for use |
Family Cites Families (7)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| FR2140116A1 (en) * | 1971-06-01 | 1973-01-12 | Diamond Shamrock Corp | Emulsion polymn of acrylamides - in perchloroethylene as dispersed phase |
| FR2251573B1 (en) * | 1973-11-21 | 1977-06-17 | Nobel Hoechst Chimie | |
| US4037040A (en) * | 1974-08-14 | 1977-07-19 | Celanese Corporation | Refluxing water-in-oil emulsion process for preparing water-soluble polyelectrolyte particles |
| GB2126591B (en) * | 1982-09-02 | 1986-07-30 | Kao Corp | Process for producing highly water absorptive polymer |
| JPS6187702A (en) * | 1984-10-05 | 1986-05-06 | Seitetsu Kagaku Co Ltd | Production of water-absorptive resin |
| JPH066612B2 (en) * | 1986-01-25 | 1994-01-26 | 住友精化株式会社 | Water absorbent resin manufacturing method |
| JPH0830098B2 (en) * | 1987-07-16 | 1996-03-27 | 日本合成化学工業株式会社 | Super absorbent resin manufacturing method |
-
1990
- 1990-08-21 JP JP2219454A patent/JP3040438B2/en not_active Expired - Lifetime
-
1991
- 1991-08-09 TW TW080106307A patent/TW203061B/zh active
- 1991-08-14 EP EP91307526A patent/EP0472362B1/en not_active Expired - Lifetime
- 1991-08-14 DE DE69116264T patent/DE69116264T2/en not_active Expired - Fee Related
- 1991-08-19 US US07/746,991 patent/US5202400A/en not_active Expired - Fee Related
- 1991-08-21 KR KR1019910014372A patent/KR100196562B1/en not_active IP Right Cessation
Also Published As
| Publication number | Publication date |
|---|---|
| KR100196562B1 (en) | 1999-06-15 |
| DE69116264D1 (en) | 1996-02-22 |
| US5202400A (en) | 1993-04-13 |
| EP0472362B1 (en) | 1996-01-10 |
| EP0472362A1 (en) | 1992-02-26 |
| JPH04100803A (en) | 1992-04-02 |
| KR920004427A (en) | 1992-03-27 |
| DE69116264T2 (en) | 1996-05-23 |
| TW203061B (en) | 1993-04-01 |
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